just curious i have a 1971 402ci what were all the heads used on these engines. The heads i have are casting number 3993820, are these heads anygood, i also have a set of 049 heads, i read were the 820s have a 113cc cobustion chamber that seems pretty small for a open chamber head. will these 820s work decent for a mild street car (71 nova) trying to get into the mid 12s.

thanks
Dustin

 

They were used on the 300 and 330 HP 402s (LS-3 engine). They also may have been used on the 454. They have 2.19/1.88 valves and should be fine as long as you arent chucking it past 6k. I did read somewhere tho that you should have them CC'ed.
As for the 113 if it is going to be NA, then the higher compression ratio would probably help abit.

 

the 049's r basically the same but with a 122 cc, which would be better for lower compression.

 

3993820....71......oval...OPEN...402, 113cc chamber, 255/114 ports